As flat panel display devices used in notebook computers, televisions (TVs), or portable phones that require thinning, miniaturization, and low power consumption, a plasma display panel (PDP), a field emission display device (FED), a thin film transistor liquid crystal display (TFT-LCD) device, etc, have been recently developed. Among these, active research into a liquid crystal display (LCD) device having excellent color reproduction and thinness has been conducted.
Among flat panel display devices, although a PDP and an FED may enable self emission, since the LCD does not enable self emission, the LCD may radiate light by using an auxiliary backlight unit that is an auxiliary light source in order to achieve an image display. The backlight unit has a structure of a surface light source, which is referred to as an edge type or a direct type, in order to meet a requirement that light be uniformly irradiated to an entire screen.